The instant invention relates to a winding device, and more particularly to a control device for controlling the contact pressure of a bobbin against its drive roller.
The winding of a delivered yarn into cross-wound bobbins on a variety of textile machines is known from the state of the art. This operation can, for instance, take place in winding machines and spinning/winding machines, e.g. rotor spinning machines. For this purpose, the winding device is as a rule equipped with a bobbin arm to hold and guide the bobbin. To drive the bobbin it is presented to a rotating roller which rotates the bobbin through friction. During the build-up of the bobbin, which is accompanied by an increase of bobbin diameter, the bobbin arm evens out the increasing bobbin diameter through a swivelling motion in such a manner that the bobbin is in contact with the roller at approximately the same location throughout the build-up.
A winding and bobbin holder is known from DE-OS 11 17 295, whereby the contact pressure of the bobbin against a roller which drives it is controlled by means of an adjustable spring. With this device, the pressure on the bobbin which is caused by gravity is at first increased as the bobbin is built up and is later lowered by means of a drive spring. The bobbin arm is here provided with a lever which supports the bobbin at one end as part of a rocking lever joint arrangement, while it is subjected at its other end to the force of a spring. During the build-up of the bobbin the rocking lever joint goes through its extended position, whereby the spring exerts force producing a pressure upon the bobbin. During further build-up of the bobbin, the rocking lever joint leaves its extended position again, so that the spring is now exerting a lifting force upon the bobbin arm. The spring force which decreases due to the extension of the spring is thereby more than compensated for by a longer lever arm upon which the spring acts. The purpose of this arrangement is to keep the contact pressure of the bobbin against the drive roller approximately constant during the entire build-up of said bobbin. Through suitable selection of the appropriate length of the rocking lever joint, it is also possible to decrease the contact pressure of the bobbin against the drive roller as the bobbin diameter increases. Depending on the application of the completed bobbin, it may be desired that the bobbin be wound with different contact pressures, e.g. with less contact pressure for dye bobbins. For other applications, it may be desired that the bobbin be wound tightly. For this purpose the spring of the winding mechanism of DE-OS 22 17 295 is provided with an adjusting screw by means of which the pre-stress of the spring can be changed. DE 25 18 646 C2 discloses a device for the control of the contact pressure of a textile bobbin in which the extension position of the rocker lever arrangement, as well as the pre-stress of the pressure spring, can be changed.
DE-OS 22 20 727 discloses a device to produce the contact pressure for bobbins in which one or two springs are intermittently assigned to a pressure device during the build-up of the bobbin. Here, too, an adjustability of pre-stress of the pressure spring, as well as a change of the lever arm on which the Spring acts, occurring simultaneously with the adjustment of spring force, is already shown.
DE 39 11 854 A1 discloses a control device for the contact pressure of a bobbin in which the bobbin arm supporting the bobbin attaches by means of a pneumatic cylinder. In this device an optimal contact pressure is determined as a function of the diameter of the bobbin, whereby the contact pressure control device maintains a pre-set contact pressure correction curve, whereby a drive mechanism of the bobbin holder is controlled via the momentary bobbin diameter. For this purpose the ratio of the bobbin's speed of rotation and that of the drive roller is detected to calculate the take-up bobbin diameter and the driving mechanism of the bobbin arm is controlled on the basis of the indicated attribution of diameter and contact pressure.
DE 24 06 122 C2 shows a wind-up device of a winding machine in which the device used to press the bobbin against the drive roller is equipped with two compression springs by means of which a resulting force is finally exerted upon the rocking lever joint arrangement, whereby the bobbin is first pressed against the drive roller and is lifted up in opposition to gravity as the bobbin diameter increases. The utilization of two springs is intended to exponentially decrease the contact pressure between bobbin and drive roller as the bobbin grows.
With ever higher standards demanded in the quality of yarns, and especially of the bobbins constituted therewith, and above all so as to satisfy the demand for greater flexibility and ease in operation, especially in spinning/winding machines, new concepts are needed in order to achieve and, at the same time, to improve results under different conditions and requirements. The change-over of spinning-winding machines to other yarn numbers or other fiber materials, as well as the requirements imposed on controllability and adjustability of the machines which are becoming more and more important in improving quality, require new concepts in solving new resulting problems. Development should also make it possible for producing different yarns on a machine, whereby it is necessary for said yarns to be wound up accordingly. This has become possible by marking each individual bobbin, because there is then no longer any danger of mixing up the different yarns. In addition, it will be required in the future in a winding mechanism that the winding conditions, i.e. the contact pressure of the bobbin, can be adapted automatically and rapidly as a function of the momentary operating situation, e.g. during piecing, after yarn breakage, when starting the yarn on the former, or during the formation of a yarn reserve. The solutions provided by the state of the art so far are no longer able to meet such new requirements.
The device of DE 25 18 646 C2, for example, has the disadvantage that only a small number of spinning stations can be adjusted simultaneously by means of its adjusting mechanism. In the spinning/winding machines normally used today, and which may have about 280 spinning stations, this device can only be used at great cost. In addition it has the disadvantage that due to the mechanical clearance, the adjusting mechanism can produce different forces at different winding stations, so that the winding of the bobbins varies from spinning station to spinning station. In addition, the adjustment of the contact pressure takes time and requires trained personnel. A change in the adjustment during operation is practically impossible, and the change cannot be automated.
The control device of DE 39 11 854 A1 requires great expenditures for the detection of the different rotational speeds as well as a costly and complicated device to control the contact pressure mechanism.
Although the devices shown otherwise in the state of the art serve their purpose in part in their special application, they are however entirely inflexible. As a result, high costs are involved when a different fiber material or a different bobbin density is to be wound, for example, or when it appears during the operation of the machine that the contact pressure must be increased or lowered.